Employees of U.S. contractor Louis-Berger Group "were boarding their helicopter and attempting to leave the site of a clinic under construction," according to a command release. News reports quoted a U.S. embassy source saying that an "unidentified assailant" fired on the employees as the helicopter was preparing to take off.

Reports indicate that the pilot was killed. Coalition forces evacuated the two seriously wounded individuals to medical facilities at Kandahar and then to Bagram, according to a command spokesman. Forces also transported the helicopter back to the base at Kandahar.

Officials said local security forces and soldiers from the 10th Mountain Division are working to apprehend the responsible individual. The command said it would continue to work closely with Afghan official and forces "to determine exactly what happened and jointly bring the perpetrators of this crime to justice."

"Coalition forces call on the tribal elders and members of Panjawi District to hand over to Afghan security or Coalition forces, the criminal who, by this action, would deny the residents of Panjawi District a vital medical clinic and other much-needed reconstruction and humanitarian aid," a command release stated.